The broad objective of this research is to gain basic knowledge about processes involved in blood pressure discrimination and control. Experimental studies will be conducted to determine the extent to which normal subjects can detect variations in their own blood pressure and whether this ability can be improved with discrimination training (knowledge of results). The effects of blood pressure discrimination training on the voluntary control of blood pressure with biofeedback training, and vice versa will also be assessed. Using a mental arithmetic task to elevate pressure, discrimination ability will be compared under stress and non-stress conditions. Subsequent research will compare hypertensives and normotensives in their ability to discriminate blood pressure. Male and female subjects in the age range 35-55 will be studied, both normotensives and mild hypertensives, the latter to be under medical care. The experiments will be conducted under computer control (DEC PDP-11/GT-40). Systolic and diastolic blood pressure will be recorded using a beat-to-beat tracking-cuff system. Other measures include: heart rate, skin conductance, respiration, and electromyographic activity. Anxiety, autonomic perception, and post-experimental questionnaires will be used. This research may help understand what internal sensations and physiological responses are associated with blood pressure variations. Blood pressure discrimination training may be useful in the behavioral management of hypertension.